How to Add to a List in Python

A list is a mutable sequence of elements surrounded by square brackets. If you’re familiar with JavaScript, a Python list is like a JavaScript array. It's one of the built-in data structures in Python. The others are tuple, dictionary, and set.

A list can contain any data type such as an integer, float, string, and boolean:

num_list = [1, 2, 3, 10]

float_list = [2.9, 3.9, 4.6]

boo_list = [True, False]

string_list = ['JavaScript', 'Python', 'freeCodeCamp']

It can also contain a mixture of those data types:

mixed_list = ['freeCodeCamp', 1, 1.1, True]

Since lists are mutable, you can add items to them or remove items from them. This article will show you how to add to a list.

Python provides 3 methods with which you can add to a list. Those methods are append(), extend(), and insert().

How to Add to a List with the `append()` Method

The append() element adds to the end of a list.

Provided we have the following list:

sports_list = ["Football", "Basketball", "Baseball", "Tennis"]

If I want to add “Cricket” to the end of that list, I can do it with the append() method this way:

sports_list.append("Cricket")

Printing sports_list to the console results in this:

['Football', 'Basketball', 'Baseball', 'Tennis', 'Cricket']

You can see Cricket was added to the last index in the list.

You can also prompt the user to add to the list this way:

sports_list = ["Football", "Basketball", "Baseball", "Tennis"]
new_sport = input("Please add a new sport: ")
sports_list.append(new_sport)

print(sports_list)

How to Add to a List with the `insert()` Method

The append() method helps you add to the end of a list, but if you want to add to any index you want, you can use the insert() method.

To use the insert() method for adding to a list, you need to specify the index, then the item you want to add:

insert(index, item)

I have added Athletics to the first index (0) of the sports_list this way:

sports_list = ["Football", "Basketball", "Baseball", "Tennis"]
sports_list.insert(0, "Athletics")
print(sports_list)

# Output: ['Athletics', 'Football', 'Basketball', 'Baseball', 'Tennis']

I also added Wrestling to index 2 (the 3rd index) this way:

sports_list.insert(2, "Wrestling")
print(sports_list)

# Output: ['Athletics', 'Football', 'Wrestling', 'Basketball', 'Baseball', 'Tennis']

How to Add to a List with the `extend()` Method

The extend() method adds an iterable data item to a list or adds one list to another list. So, with it, you can add a tuple, set, or dictionary to a list.

sports_list = ["Football", "Basketball", "Baseball", "Tennis"]

# add another list
sports_list.extend(["Golf", "Boxing"])

# Append a tuple
sports_list.extend(("Netball", "TT"))

print(sports_list)

# Output: ['Football', 'Basketball', 'Baseball', 'Tennis', 'Golf', 'Boxing', 'Netball', ‘TT']

How to Add a Dictionary to a List with the `append()` Method

If you try to add a dictionary to a list with the extend() method, you only get the keys and not the values:

sports_list = ["Football", "Basketball", "Baseball", "Tennis"]
sports_dict = {1: "Netball", 2: "Chess"}

sports_list.extend(sports_dict)
print(sports_list)
# Output:  ['Football', 'Basketball', 'Baseball', 'Tennis', 1, 2]

You can loop through the dictionary and then use the append method to add it to the list. This will give you the dictionary’s keys and values as a set of tuples in the list:

sports_list = ["Football", "Basketball", "Baseball", "Tennis"]
sports_dict = {1: "Netball", 2: "Chess"}

for k, v in sports_dict.items():
    sports_list.append((k, v))

print(sports_list)

# Output: ['Football', 'Basketball', 'Baseball', 'Tennis', (1, 'Netball'), (2, 'Chess')]

If you want the dictionary as it is right inside the list, you can just use the append method without a loop:

sports_list = ["Football", "Basketball", "Baseball", "Tennis"]
sports_dict = {1: "Netball", 2: "Chess"}

sports_list.append(sports_dict)
print(sports_list)

# Output: ['Football', 'Basketball', 'Baseball', 'Tennis', {1: 'Netball', 2: 'Chess'}]

Conclusion

In this article, we looked at how to use the append(), insert(), and extend() methods to add to a list in Python.

What you add to a list does not have to be a single element. That’s why I showed you how to use the extend() method to help you add iterables like lists, tuples, and dictionaries to a list.

Thank you for reading.

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